Backcountry Camping in Wind: Field Notes from the Colorado Alpine

Sponsored by Brynje

Is your base layer working for you or against you when hiking in inclement weather?

In cold-weather layering systems, the base layer is the interface between skin physiology and the rest of the clothing stack. Its job is not just “warmth.” It is moisture control: limiting liquid water accumulation next to the skin, preserving midlayer insulation performance, and reducing evaporative cooling during stop-and-go activity.

Brynje approaches that problem with a polypropylene fishnet structure (see Super Thermo and Super Micro). Two design choices matter here:

Fiber chemistry (polypropylene): Polypropylene is highly hydrophobic and absorbs essentially no water into the fiber. In practical terms, that means the yarns do not readily take on moisture and become heavy or clammy. Because the fibers resist wetting, the fabric is less likely to retain liquid water within the textile matrix than more absorbent fibers, and it tends to dry quickly when ventilation and heat are available.

Fabric architecture (large-pore mesh): The fishnet structure creates a high void fraction: a large percentage of the “fabric” volume is actually air space. That geometry reduces the contact area between fabric and skin, which can reduce the sensation of wet cling and allows perspiration vapor to move away from the skin surface more directly. The large pores also support rapid air exchange when outer layers are vented, helping maintain a drier microclimate at the skin. The result is a base layer that prioritizes moisture management and microclimate stability over the “uniform coverage” approach of traditional jersey knits.

In practice, fishnet base layers are often paired with a thin, more continuous layer above them (or used strategically by activity level and temperature) to balance moisture control, convection management, and comfort across a range of conditions.